1) Field of the Invention
The present invention relates to a stent and, in particular, to a stent that is capable of facilitating fluid flow between a bifurcated lumen and the stent.
2) Description of Related Art
Stents are devices that are inserted into body lumina such as vessels or passages to keep the lumen open and prevent closure due to a stricture, external compression, or internal obstruction. In particular, stents are commonly used to keep blood vessels open in the coronary arteries, and they are frequently inserted into the ureters to maintain drainage from the kidneys, the bile duct for pancreatic cancer or cholangiocarcinoma, or the esophagus for strictures or cancer. Vascular as well as nonvascular stenting has evolved significantly; unfortunately, there remain significant limitations with respect to the technology for stents implanted proximate to a bifurcated lumen within various portions of a patient's anatomy.
A lumen or similar conduit, which, along its course, extends a major branch vessel, is termed a “bifurcating” lumen. The structural point of bifurcation, where the main trunk lumen and its side branch lumen meet, is termed the origin of the side branch, and the structure forming the angle between the lumina is termed the “carina.” Furthermore, two bifurcated side branches may converge to form a single lumina. For instance, the liver includes left and right hepatic ducts extending therefrom and that converge to form the common hepatic duct. The common hepatic duct joins with the bile duct, where the bile duct carries bile to the duodenum for digestion. The gall bladder includes a side branch (i.e., cystic duct) that extends between the gall bladder and the common hepatic duct. As such, bile may flow between the common hepatic duct and gall bladder via the cystic duct for storing bile when digestion is not occurring and between the gall bladder and bile duct when digestion occurs.
Accordingly, management of bifurcating lumina involves treatment of both the main trunk lumina across the origin of the side branch as well as the origin and/or proximal segment of the side branch. Attempts to treat bifurcated lumina have traditionally been by the serial installation of multiple stents or the simultaneous installation of modular stents (i.e., stents comprising a plurality of standardized units for use together in a cumulative group). In particular, attempts have been made to provide devices that allow the deployment of separate stents into each side branch. In addition, a bifurcated stent, such as the one disclosed in U.S. Patent Application Publication No. 20040220653 (application Ser. No. 10/427,539), entitled “Bifurcated Medical Appliance Delivery Apparatus and Method,” which is incorporated herein by reference, discloses an integrated stent that cradles the corina between the arms of the bifurcated stent as each arm of the bifurcated stent is delivered to a respective side branch.
Furthermore, complications may arise proximate to a bifurcation that require stenting, such as within the bile duct between the hepatic ducts and the duodenum. Providing a bifurcated stent, such as that described above, is typically difficult to position within each of the hepatic ducts. Moreover, if a stent is positioned within one of the hepatic ducts and along the bile duct, the unstented hepatic duct may be adversely affected, such as by limiting or eliminating the flow of bile between the unstented hepatic duct and the common hepatic duct and bile duct. In addition, similar complications may arise where a stent extends between a hepatic duct and the duodenum and across the opening of the cystic duct.
Thus, there is a need in the industry for a stent that facilitates fluid flow between a side branch of a bifurcated lumen and the stent. In addition, there is a need for a stent that is capable of being easily positioned proximate to a side branch of a bifurcated lumen requiring fluid flow between the branch and the stent.